Aryl hydrocarbon receptor-dependent upregulation of Cyp1b1 by TCDD and diesel exhaust particles in rat brain microvessels

<p>Abstract</p> <p>Background</p> <p>AhR activates the transcription of several target genes including CYP1B1. Recently, we showed <it>CYP1B1 </it>as the major cytochrome P450 (CYP) enzyme expressed in human brain microvessels. Here, we studied the effect of AhR activation by environmental pollutants on the expression of Cyp1b1 in rat brain microvessels.</p> <p>Methods</p> <p>Expression of AhR and Cyp1b1 was detected in isolated rat brain microvessels. AhR was immunovisualised in brain microvessel endothelial cells. The effect of AhR ligands on Cyp1b1 expression was studied using isolated brain microvessels after <it>ex vivo </it>and/or <it>in vivo </it>exposure to TCDD, heavy hydrocarbons containing diesel exhaust particles (DEP) or Δ⁹-tetrahydrocannabinol (Δ⁹-THC).</p> <p>Results</p> <p>After <it>ex vivo </it>exposure to TCDD (a highly potent AhR ligand) for 3 h, <it>Cyp1b1 </it>expression was significantly increased by 2.3-fold in brain microvessels. A single i.p. dose of TCDD also increased <it>Cyp1b1 </it>transcripts (22-fold) and Cyp1b1 protein (2-fold) in rat brain microvessels at 72 h after TCDD. Likewise, DEP treatment (<it>in vivo </it>and <it>ex vivo</it>) strongly induced Cyp1b1 protein in brain microvessels. DEP-mediated Cyp1b1 induction was inhibited by actinomycin D, cycloheximide, or by an AhR antagonist. In contrast, a sub-chronic <it>in vivo </it>treatment with Δ⁹-THC once daily for 7 seven days had no effect on <it>Cyp1b1 </it>expression</p> <p>Conclusions</p> <p>Our results show that TCDD and DEP strongly induced Cyp1b1 in rat brain microvessels, likely through AhR activation.</p

Blocking TGF-β signaling pathway preserves mitochondrial proteostasis and reduces early activation of PDGFRβ+ pericytes in aristolochic acid induced acute kidney injury in wistar male rats

The platelet-derived growth factor receptor β (PDGFRβ)+ perivascular cell activation becomes increasingly recognized as a main source of scar-associated kidney myofibroblasts and recently emerged as a new cellular therapeutic target.In this regard, we first confirmed the presence of PDGFRβ+ perivascular cells in a human case of end-stage aristolochic acid nephropathy (AAN) and thereafter we focused on the early fibrosis events of transforming growth factor β (TGFβ) inhibition in a rat model of AAN.Neutralizing anti-TGFβ antibody (1D11) and its control isotype (13C4) were administered (5 mg/kg, i.p.) at Days -1, 0, 2 and 4; AA (15 mg/kg, sc) was injected daily.At Day 5, 1D11 significantly suppressed p-Smad2/3 signaling pathway improving renal function impairment, reduced the score of acute tubular necrosis, peritubular capillaritis, interstitial inflammation and neoangiogenesis. 1D11 markedly decreased interstitial edema, disruption of tubular basement membrane loss of brush border, cytoplasmic edema and organelle ultrastructure alterations (mitochondrial disruption and endoplasmic reticulum edema) in proximal tubular epithelial cells. Moreover, 1D11 significantly inhibited p-PERK activation and attenuated dysregulation of unfolded protein response (UPR) pathways, endoplasmic reticulum and mitochondrial proteostasis in vivo and in vitro.The early inhibition of p-Smad2/3 signaling pathway improved acute renal function impairment, partially prevented epithelial-endothelial axis activation by maintaining PTEC proteostasis and reduced early PDGFRβ+ pericytes-derived myofibroblasts accumulation

Améliorer le ciblage tissulaire des anticorps thérapeutiques par de nouveaux formats : l’exemple de la barrière hémato-encéphalique

International audienc

Transient Receptor Potential Vanilloid in the Brain Gliovascular Unit: Prospective Targets in Therapy

The gliovascular unit (GVU) is composed of the brain microvascular endothelial cells forming blood–brain barrier and the neighboring surrounding “mural” cells (e.g., pericytes) and astrocytes. Modulation of the GVU/BBB features could be observed in a variety of vascular, immunologic, neuro-psychiatric diseases, and cancers, which can disrupt the brain homeostasis. Ca2+ dynamics have been regarded as a major factor in determining BBB/GVU properties, and previous studies have demonstrated the role of transient receptor potential vanilloid (TRPV) channels in modulating Ca2+ and BBB/GVU properties. The physiological role of thermosensitive TRPV channels in the BBB/GVU, as well as their possible therapeutic potential as targets in treating brain diseases via preserving the BBB are reviewed. TRPV2 and TRPV4 are the most abundant isoforms in the human BBB, and TRPV2 was evidenced to play a main role in regulating human BBB integrity. Interspecies differences in TRPV2 and TRPV4 BBB expression complicate further preclinical validation. More studies are still needed to better establish the physiopathological TRPV roles such as in astrocytes, vascular smooth muscle cells, and pericytes. The effect of the chronic TRPV modulation should also deserve further studies to evaluate their benefit and innocuity in vivo

Reduced Pupil Diameter in Volunteers on Stable Buprenorphine Maintenance Therapy with Telaprevir: a Drug-Drug Interaction Involving P-Glycoprotein at the Blood-Brain Barrier?

International audienc

Is extracorporeal treatment useful for managing severe baclofen poisoning? – The debate is still open

International audienc

Apport de la protéomique quantitative dans la caractérisation de transporteurs et enzymes modulant le passage des médicaments au travers de la barrière hémato-encéphalique

Depuis sa découverte au début du 20e siècle, la barrière hémato-encéphalique (BHE) a longtemps été considérée comme une  ≪ barrière physique ≫ limitant l’entrée dans le cerveau de composés ayant soit un haut poids moléculaire soit une forte polarité. Dans les années 50, la découverte de systèmes de transport assurant l’entrée cérébrale de composés endogènes tels que le glucose et les acides aminés a conduit à lui donner le nom de  ≪ barrière biochimique ≫ permettant une nutrition sélective du cerveau. Depuis une vingtaine d’années, la pharmacologie des médicaments du système nerveux central s’est vue totalement reconsidérée en raison de la détection au niveau de la BHE de systèmes de transport des médicaments facilitant ou au contraire s’opposant à leur entrée dans le cerveau mais également d’enzymes du métabolisme des médicaments. Le développement de la biologie moléculaire et de méthodes analytiques extrêmement sensibles, telles que la spectrométrie de masse en tandem appliquée au dosage de protéines, a permis d’identifier non seulement la nature mais également la quantité de chacune de ces protéines au niveau de la BHE. Appliquées dans un premier temps aux modèles animaux utilisés en pharmacologie expérimentale, ces techniques ont plus récemment permis de quantifier ces transporteurs et enzymes au niveau de la BHE humaine. Une des applications possibles de ces travaux consisterait à concevoir des nouveaux médicaments en fonction de leur capacitaé interagir avec ces transporteurs de manière à permettre leur vectorisation dans le cerveau

Respiratory effects of diazepam/methadone combination in rats: A study based on concentration/effect relationships. Respiratory effects of diazepam/methadone combination in rats: a study based on concentration/effect relationships

Abbreviations: ANOVA, analysis of variance; AUC, area under the curve; BZD, benzodiazepine; CYP, cytochrome P450; DZP, diazepam; EDDP, 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine; f, respiratory frequency; HPLC/MS, high performance liquid chromatography-mass spectrometry; LD 50 , lethal dose 50%; NADPH, nicotinamide adenine dinucleotide phosphate; PaO 2 , arterial oxygen partial pressure; PaCO 2 , arterial carbon dioxide partial pressure; T I , inspiratory time; T E , expiratory time; T TOT , total respiratory time; V E , minute volume; V T , tidal volume. 2 ABSTRACT Methadone may cause respiratory depression and fatalities. Concomitant use of benzodiazepines in methadone-treated patients for chronic pain or as maintenance therapy for opiate abuse is common. However, the exact contribution of benzodiazepines to methadone-induced respiratory toxicity remains debatable. We investigated the respiratory effects of the combination diazepam (20 mg/kg)/methadone (5 mg/kg) in the rat, focusing on methadone concentration/effect relationships. Respiratory effects were studied using arterial blood gases and whole-body plethysmography. Plasma concentrations of both Rand S-methadone enantiomers were measured using high-performance liquid chiral chromatography coupled to mass spectrometry. To clarify mechanisms of diazepam/methadone interaction, methadone metabolism was investigated in vitro using rat liver microsomes. Diazepam/methadone co-administration significantly increased methadone-related effects on inspiratory time (p &lt; 0.001) but did not significantly alter the other respiratory parameters when compared with methadone alone, despite significant increase in the area under the curve of plasma R-methadone concentrations measured during 240 min (p &lt; 0.05). Diazepam/methadone co-incubation with microsomes in vitro resulted in a significant inhibition of methadone metabolism (p &lt; 0.01), with 50%-inhibitory diazepam concentrations of 25.02 ± 0.18 µmol/L and 25.18 ± 0.23 µmol/L for R-and S-methadone, respectively. We concluded that co-administration of high-doses of diazepam and methadone in rats is not responsible for additional respiratory depression in comparison to methadone alone, despite significant metabolic interaction between the drugs. In humans, although our experimental data may suggest the relative safety of benzodiazepine/methadone coprescription, physicians should remain cautious as other underlying conditions may enhance this drugdrug interaction

Gliclazide disposition in overdose – a case report with pharmacokinetic modeling

International audienc